It is possible to examine the presence or absence of a nucleic acid (DNA or RNA) originating in a virus or a bacteria and the presence or absence of a nucleic acid originating in the mutant gene related to a specific disease or diathesis so as to accurately diagnose an infection, a genetic disorder such as a tumor, a diathesis, and the like. For example, for diagnosing the presence or absence of a viral infection, a specimen is obtained from the mucous membrane of the patient and the like to perform a process for amplifying only the nucleic acid originating in the virus using a PCR method. When the nucleic acid originating in the virus is detected in the specimen obtained in this process, the patient can be determined to be infected by the virus. Nowadays, the development of genome analysis causes accumulation of information related to the base sequence of the nucleic acid such as a gene. Additionally, the improvement of the PCR method facilitates selectively amplifying the nucleic acid originating in the virus or in the bacteria or the nucleic acid originating in the specific mutant gene. Therefore, for further popularization of the application of the above-described diagnosis method for the nucleic acid, there is the need for a technique for simply determining presence or absence of a specific nucleic acid.
As a technique for simply determining the presence or absence of the specific nucleic acid (hereinafter referred to as “the target nucleic acid”), there is proposed an inspection tool for nucleic acid chromatography (in Patent Documents 1 and 2) . This inspection tool for nucleic acid chromatography expands a liquid specimen in a porous sheet using a system similar to that of paper chromatography, and captures the target nucleic acid contained in the specimen using a nucleic acid probe fixed to the surface of the porous sheet. Furthermore, the captured target nucleic acid is colored to indicate the detection of the target nucleic acid on the surface of the porous sheet. Thus, in the inspection tool for nucleic acid chromatography, in the case where the target nucleic acid is contained in the specimen, the indication appears on the surface of the porous sheet. On the other hand, in the case where the target nucleic acid is not contained in the specimen, the indication does not appear on the surface of the porous sheet. with this extremely simple system, it is possible to determine the presence or absence of the target nucleic acid.
Typically, the inspection tool for nucleic acid chromatography is widely used as a test piece (this is ordinarily referred to as “the strip”) made by attaching the porous sheet in an elongated rectangular shape to a board (backing sheet) in an elongated rectangular shape (in Patent Documents 3 and 4). For example, in the case where the target nucleic acid is labeled with dye in advance when the specimen is prepared, insertion of the distal end portion of the above-described strip into a test tube containing the specimen causes capillary action to expand the specimen in the porous sheet without any subsequent operation. Then, the target nucleic acid is captured and accumulated in the position where the nucleic acid probe is fixed in the porous sheet. This allows coloring the porous sheet surface (in the portion where the nucleic acid probe is fixed). Accordingly, multiple specimens can be simultaneously inspected even with a very simple work of only inserting the strips of the inspection tool for nucleic acid chromatography in respective multiple test tubes, as an advantage.